The homework help thread...(SERIOUS)

[Rain22]

Anybody know how to do titration problems in chemistry?

I have 3 but here's one of them. I'm hoping to learn how to do it so i can do the other two by myself. Thanks for the help!

Determine the volume of .020 M HCl solution needed to neutralize 20.0 mL of 0.56 M NaOH

You gotta equate the moles of each (knowing that HCl + NaOH ---> NaCl + H2O) with the formula n = c*V (moles = concentration * volume)
Since the moles of each reactant are equal:
c1V1 = c2V2
0.56M*20mL = 0.02M*V2
V2 = 560 mL

[aggieman122]

ok, so my teacher keeps giving us problems without teaching us how to do them. Here's two more.. I would really appreciate any help I can get.

A 1.0 L solution of HCl has a pH=1. How many liters of distilled water must be added to change the pH to 2?
AND
6 g of LiOH is added to water to make 500 ml of solution. What is the pH?

Also if you explain how you did it, that would be awesome!

[Rain22]

ok, so my teacher keeps giving us problems without teaching us how to do them. Here's two more.. I would really appreciate any help I can get.

A 1.0 L solution of HCl has a pH=1. How many liters of distilled water must be added to change the pH to 2?
AND
6 g of LiOH is added to water to make 500 ml of solution. What is the pH?

Also if you explain how you did it, that would be awesome!

Okay, for the first one you need to know the equation pH = -log[H+] (where [H+] is the molar concentration of hydrogen ions)
HCl is a strong acid so we assume it completely dissociates in water into H+ and Cl- ions. You know the pH so:
pH = -log[H+]
1 = -log[H+]
-1 = log[H+]
[H+] = 10^(-1)
[H+] = 0.1M

Now you need the concentration when pH=2
2 = -log[H+]
[H+] = 10^(-2)
[H+] = 0.01M

Because you're only adding water, the moles of HCl stay the same. So like your question before:
c1V1=c2V2
0.1M*1L = 0.01M*V2
V2 = 10L

So your final volume is 10L, but because your initial was 1L, it means you have to add 9L of water (10-1=9 lol).


For your second question, first calculate moles of LiOH:
n = m/M
n = 6/M --->don't have calculator or molar mass on hand, but you can do this..

take your answer and find concentration of OH- ions (knowing that LiOH is a strong base and produces Li+ and OH- in water)
c = n /V
c = n/0.5L ---> which gives you concentration in moles/L

then use the equation:
ph = 14 + log[OH-]
plug in your concentration for OH- from previous calc and you're done.

Sorry if there's any erros, been a few semesters since i last took chem..

[DahStoryTella]

Trig question.

I just started a trig class on Monday (classes go quickly at this school), and we did Trig Functions of General Angles.

A portion of my assignment was finding the measure of the reference angle of the given theta. I'm a bit stuck on this one, 98.2 because it's a decimal. I know that it ends up in Quadrant Two, so do I just do the usual 180-98.2 (81.8)? Or, is it a different process because it's a decimal?

[lolmuscle129]

Trig question.

I just started a trig class on Monday (classes go quickly at this school), and we did Trig Functions of General Angles.

A portion of my assignment was finding the measure of the reference angle of the given theta. I'm a bit stuck on this one, 98.2 because it's a decimal. I know that it ends up in Quadrant Two, so do I just do the usual 180-98.2 (81.8)? Or, is it a different process because it's a decimal?

it would be the same process.

[sambnz]

This ones for anyone doing any kind of health science/sports psychology..
Just need a few ideas for how to write this out..only need a small paragraph..

Explain the relationship between Anxiety, arousal and sporting performance?

[Archie824]

Tmisc, I have to turn in this essay tomorrow, mind skimming over it and pointing out any mistakes? measly rep in return.


https://docs.google.com/document/d/1...thkey=CK2ikaMO


Warning: English is my second language.

[Hughsey1995]

Tmisc, I have to turn in this essay tomorrow, mind skimming over it and pointing out any mistakes? measly rep in return.


https://docs.google.com/document/d/1...thkey=CK2ikaMO


Warning: English is my second language.

Just realised your post is 12 hours old but just in case your still in case you still want it editing I read through it and considering English is your second language there are very few errors. I edited it to how I would write it here in the UK but I left the American spellings in it. This is my edited version:


Time magazine is a magazine which targets working adults and contain articles about politics, economics, and the highlights of the world news. The Hyatt credit card, a credit card offered by Hyatt hotel, was advertised in the September 2010 issue. The working class adult who travels; requires use of hotel; or is planning a vacation is targeted by this ad. The advertisement’s main purpose is to convince people to apply for and use the credit card. There are several methods that the advertiser uses to try and convince people to apply for the credit card including its layout, artwork and language.

The layout is an essential part to draw people’s attention to the main area of the ad. The ad consists of 3 sections, the large picture, the center, and the bottom. The large picture shows the hotel’s relaxing poolside. There is a gray border box in the center of the page, in it quoting “simplicity is the ultimate sophistication” by Leonardo Da Vinci. On the bottom left of the box lays a picture of the credit card. Since the gray border box isn’t completely visible due to the credit card lying on the bottom left on top of the border, one’s eye is immediately drawn to the credit card that writes Hyatt. On the bottom is a gray section, which is directly underneath the picture of the credit card. Immediately after looking at the center, the ad leads you from the center to the credit card, and from the credit card to the bottom gray

Archie824
section with it’s message. This layout is very effective and it leads you throughout the entire message of the ad.

The ad’s artwork is important in convincing the audience to apply. Artworks can change the mood of the audience and give them a picture of the feeling they get if they apply for the credit card. The whole advertisement is portrayed on a big picture of a peaceful hotel poolside. It appears peaceful due to the still blue water, the poolside where the woman in a bathrobe is walking, the comfortable looking beach chair and all the plants around the place. When the viewer sees these features the idea of paradise should come up in their mind. The color of the border, the credit card, and the message area is gray. This color symbolises simplicity, professionalism, and sophistication. The ad gives the impression that if people have the Hyatt hard, they will also have relaxation, and they will appear professional, and sophisticated to other people.
The advertisement gives many messages to the reader. Starting off at the center of the page, the ad quotes “simplicity is the ultimate sophistication.” above the credit card. The message this sends the reader is that the card will make them look sophisticated. The bottom of the ad is the description area and at the top of that area writes, “Welcome to the Hyatt card. Simplicity at its most rewarding.” First, Hyatt is name of a hotel, a business. Anytime a customer goes into a business,
Archie824
the business has to greet, and make the customer feel welcome. The message continues with “Begin with two nights at any Hyatt anywhere in the world.” Not only do you get the pleasure of knowing that you look sophisticate to other people, but you also get a free two nights stay at their hotel. This is an attractive offer to many business persons or anybody looking for a vacation. The ad also states that it’s simple to get rewards from this card, and the simpler they are, the more rewarding they feel. The ad is telling the reader that if you get this card, you will feel sophisticated, and rewarded making it appealing to them.

The Advertisement is successful at making the audience want the card. The layout, artwork, and language work together and are very successful at meeting the adverts purpose. This advertisement rewards the audience and makes them feel good about having it.

Has anyone really been far even as decided to use even go want to do look more like?



Hope this helps bro.

[laxingbadger]

sss

People want this so here it is.

Additional mod note by Arlecchino: Serious thread is serious. On that note, I will try and get whatever mods I can to stop by from time to time. Many of us are reasonably well educated, and some of us have collegiate teaching experience and other related experience that may be of use. No promises, will see what I can do.

Please do not crap up the thread.

OT and non-serious posts have been deleted.

Keep the thread that way.

[lucas2]

This ones for anyone doing any kind of health science/sports psychology..
Just need a few ideas for how to write this out..only need a small paragraph..

Explain the relationship between Anxiety, arousal and sporting performance?

Being under-aroused causes the athlete to react slowly to cues in the environment, causing the person to miss a catch or a hit for example.
Being over-aroused causes the athlete to see cues that may not be there, for example; he may think he saw the football coming towards him faster than he expected, therefore he drops the catch.
Finding the optimal level of arousal is somewhere between being over-aroused and under-aroused.

[Strengthftw]

Does anyone know any cool famous contemporary artist I could write a research paper about? Also need to draw too

[joebus36]

Chemistry Help Please!!

How many liters of carbon dioxide will be obtained by the combustion of 50 kg of coal (carbon)?

[QT]

not bad, but i edited a few things in bold(may want to revise my revision since adding on to someone else's words at fragmented junctions isnt the best way to write something)

Thanks, repped. Could you just delete what you quoted so that my teacher can't find this on the web^^ ?

Cheers.

[saharaman]

Hey guys, I need to find an article showing that simple carbs cause a fast increase in insluin levels and then a crash down, and that complex carbs causes a steady increase without the crash.

Thanks a lot.

[N4J4R]

Check out this link if you need help with finance, chemistry, calculus, statistics and much much more!

http ://www.khanacademy.org/

^^remove space before ':'

Hope this helps!!!

[NWDub]

If anyone needs econ/business, help. Did DECA and all the chit in highschool going to major in Econ. Taking the principles courses right now at my uni, PM me.

[UpInHawaii]

Hey guys I was helping my bro with his english culminating and had some questions. His task to is compare 2 movies by a director. He picked Gray f. Gary (Law abiding Citizen and Italian Job) Does anyone know what he could compare, and what are the directors trade marks in this?

[shanny66]

Describe how farmers have adapted to the steep slopes in fold mountain areas?

[Pizzownage]

Describe how farmers have adapted to the steep slopes in fold mountain areas?

They use terrace farming. Cutting into the slope to be able to use the land in the most efficient way possible.

[Alex2010]

if a pound of turkey costs .79$, how much will q pounds of turkey cost?

wtf is this? im trying to help my little brother i dont remember this from my algebra

[Pizzownage]

if a pound of turkey costs .79$, how much will q pounds of turkey cost?

wtf is this? im trying to help my little brother i dont remember this from my algebra

thats not enough information to be a question?... lol

[NitroStigs]

if a pound of turkey costs .79$, how much will q pounds of turkey cost?

wtf is this? im trying to help my little brother i dont remember this from my algebra

??? q as in Q? What the hell lol. you sure q doesnt equal a number? Like how much will 9lb of turkey cost @ .79$ if q=9lb? I dont understand the question bro lol

[Pizzownage]

??? q as in Q? What the hell lol. you sure q doesnt equal a number? Like how much will 9lb of turkey cost @ .79$ if q=9lb? I dont understand the question bro lol

yeah. there needs to be like a FIND______

[Alex2010]

wrote it word for word from his review sheet, i didnt get it either man, im like wtf?

[Alex2010]

the only other thing it says is to fill in the answer

the cost of q pounds of turkey is $____

[Pizzownage]

q=79cents per pound lol

[Alex2010]

im thinking the answer is $.79q??

here are the last two problems which i dont remember as well but i kno are not too difficult

pure acid is to be added to a 10% acid solution to obtain 90L of 18% solution. what amounts of each should be used?

and the other one, same type

$6300, part of it at 10% and part of it at 9%. for a certain year, the total yield is 598$. how much was invested at each rate?

[Pizzownage]

im thinking the answer is $.79q??

here are the last two problems which i dont remember as well but i kno are not too difficult

pure acid is to be added to a 10% acid solution to obtain 90L of 18% solution. what amounts of each should be used?

and the other one, same type

$6300, part of it at 10% and part of it at 9%. for a certain year, the total yield is 598$. how much was invested at each rate?

god damn, what is this for??

[Alex2010]

god damn, what is this for??

algebra honors breh, too much?

[Pizzownage]

algebra honors breh, too much?

Yeh man, I got an AP calc exam tomorrow lol. Calculus makes you forget how to add and do simple math. I now overanalyze everything ;(